plano/demos/use_cases/model_choice_with_test_harness

Model Choice Newsletter Demo

This folder demonstrates a practical workflow for rapid model adoption and safe model switching using Plano (plano). It includes both a minimal test harness and a sample proxy configuration.

---

Step-by-Step Walkthrough: Adopting New Models

Part 1 — Testing Infrastructure

Goal: Quickly evaluate candidate models for a task using a repeatable, automated harness.

1. Write Test Fixtures

Create a YAML file (evals_summarize.yaml) with real examples for your task. Each fixture includes:

• input: The prompt or scenario.
• must_include: List of anchor words that must appear in the output.
• schema: The expected output schema.

Example:

# evals_summarize.yaml
task: summarize
fixtures:
  - id: sum-001
    input: "Thread about a billing dispute…"
    must_include: ["invoice"]
    schema: SummarizeOut
  - id: sum-002
    input: "Thread about a shipping delay…"
    must_include: ["status"]
    schema: SummarizeOut

2. Candidate Models

List the model aliases (e.g., arch.summarize.v1, arch.reason.v1) you want to test. The harness will route requests through plano, so you don’t need provider API keys in your code.

3. Minimal Python Harness

See bench.py for a complete example. It:

• Loads fixtures.
• Sends requests to each candidate model via plano.
• Validates output against schema and anchor words.
• Reports success rate and latency.

Example usage:

uv sync
python bench.py

Benchmarks:

• ≥90% schema-valid
• ≥80% anchors present
• Latency within SLO
• Cost within budget

---

Part 2 — Network Infrastructure

Goal: Use a proxy server (plano) to decouple your app from vendor-specific model names and centralize control.

Why Use a Proxy?

• Consistent API across providers
• Centralized key management
• Unified logging, metrics, and guardrails
• Intent-based model aliases (e.g., arch.summarize.v1)
• Safe model promotions and rollbacks
• Central governance and observability

Example Proxy Config

See config.yaml for a sample configuration mapping aliases to provider models.

---

How to Run This Demo

1. Install uv (if not already installed):

   curl -LsSf https://astral.sh/uv/install.sh | sh
   

2. Install dependencies:

• Install all dependencies as described in the main Plano README (link)
• Then run

  uv sync
  

3. Start Plano

    run_demo.sh
   

4. Run the test harness:

   python bench.py
   

---

Files in This Folder

• bench.py — Minimal Python test harness
• evals_summarize.yaml — Example test fixtures
• pyproject.toml — Python project configuration
• config.yaml — Sample plano config (if present)

---

Troubleshooting

• If you see Success: 0/2 (0%), check your anchor words and prompt clarity.
• Make sure plano is running and accessible at http://localhost:12000/.
• For schema validation errors, ensure your prompt instructs the model to output the correct JSON structure.